docs: describe TTL-first leases end state, accept ADR 0004 (PR C)

[V3RON]

Part of #114. PR C of three: the documentation, changelog, and ADR status change for ADR 0004. No code — PR A (client renew timers) and PR B (daemon, config, protocol 4) land the implementation separately. Meant to be re-based onto PR B's branch before merge, which is why this touches nothing but .md files.

Release note: @release-it/conventional-changelog prepends a generated section at release time, so the hand-written ## Unreleased block has to be folded into the next generated entry rather than left beside it.

The ADR is the specification, and this PR is what accepts it

docs/adr/0004-ttl-first-leases-on-every-transport.md moves from Proposed to Accepted — not yet implemented, and its row in docs/adr/README.md matches. Per that file's status vocabulary, the docs describe the decided end state and the code catches up in PRs A and B.

Successive review rounds kept finding the same shape of problem: a doc settling something the ADR had not recorded, which inverts the rule that the ADR is the specification. So the decisions live in the record, and the docs cite it.

Decision 2 carries MCP's reconnect rule — its renew timer drives the reconnect, but only ever to a daemon that is already listening, because auto-launch must stay a tool-call concern so an operator's daemon stop is not undone by an idle session — and the renew-failure rule: a transient failure is retried on the next tick, while a renew answered UNKNOWN_LEASE ends the holder the way a lease-lost push does. Decision 4 carries the renew-width rule (a lease records the width it was granted with; a renew naming no ttlMs re-applies that width, so a four-hour lease does not shrink to fifteen minutes) and states that lease.detachedTtlMs is renamed in the key set, not aliased. Consequences grant, one bullet each: the events-payload exception to docs/agent-rules/events.md rule 6; the HTTP additive-evolution exception; lastRenewedAt replacing the derived lastHeartbeatAt decoration; protocol 4 advertised {min: 4, max: 4} under ADR 0003 §6's honesty rule; and the two TTL keys validated together at load, with a violating config failing the daemon start. The SIGKILL consequence no longer says "at most lease.defaultTtlMs", which was wrong for any lease that asked for more.

The Supersedes line names every ADR 0003 section 0004 narrows: §3's lease.heartbeat row, §8's push and held set, §9's held-ttlMs rule, §10's onLeaseLost on connection loss, and §10/§11's lazy-only MCP reconnect. ADR 0003 and 0005 are untouched, as is docs/agent-rules/events.md (the rule-6 wording is a follow-up).

The decisions, in one place

• One kind of lease. TTL-bound on every transport; lease.renew before the deadline is the only thing that keeps it alive.
• The lease stores its ttlMs. A body-less renew re-applies that width; lease.defaultTtlMs applies to a request that names no ttlMs and nowhere else — which is what makes the holder's timer safe, since it sends no TTL at all. Cadence is one third of the lease's TTL.
• lease.maxTtlMs bounds what is asked for, not what already exists. Lowering it does not shorten a lease already holding a larger stored width; that lease keeps re-applying it until released or renewed with an explicit smaller --ttl.
• Connection close means nothing to a lease — but the CLI holder does not reconnect (ADR 0003 §10): it writes one DAEMON_CONNECTION_LOST line naming the lease id and ttlDeadline and exits 1, leaving the lease standing. Exit 14 stays narrower: the daemon ended the lease while the connection was alive.
• A SIGKILLed holder keeps its device until expiresAt — at most the lease's own TTL after its last renew.
• Config: no detachedTtlMs alias; retired keys warn and are ignored, while a self-contradicting TTL pair is rejected at load and the daemon does not start.
• Cross-process lease renew needs an admin credential, exactly as cross-process release does — a lease belongs to the session it was granted to.

What each doc now says

• docs/CLI.md — simlock lease prints the grant and stays alive, renewing at one third of the lease's TTL and releasing on exit, parent death, or SIGINT/SIGTERM; transient-renew and UNKNOWN_LEASE outcomes stated. New --ttl; new connection-loss block; lease renew keeps the lease's own width and carries the admin-credential clause, as does the --detach bullet. lease renew joins the admin command list and the worked cross-invocation example. The grant example carries the full contract shape — ttlMs and lastRenewedAt included, mode gone. list --leases documents lastRenewedAt; status renders "last renewed"; the exit-code note records the exit-14 exception; the daemon section covers a stop (ends connections, not leases) and a config-refused start; simlock mcp documents lease_simulator's ttlMs and which reconnect trigger may launch a daemon. A pre-existing broken code fence around the grant example is closed.
• docs/CLIENT.md — renewing is the frontend's job, with the stored-ttlMs rule. "One connection, no reconnect" gains "A dead connection is not a dead lease"; onLeaseLost no longer fires with daemon-connection-lost; both MCP reconnect triggers and their different powers; the CLI bullet states the holder exits 1 while its lease stands.
• docs/HTTP-API.md — "detached-only over HTTP" becomes "TTL-bound, the same as everywhere else". The additive-evolution paragraph lists all three breaks — mode gone from the record the operator routes serialize, lastRenewedAt and the stored ttlMs new on it, ttlMs above the cap now 400, and the reported ttlMs being the lease's own width — instead of wrongly claiming no field is added or removed. notices is HTTP-side LeaseNoticeBuffer state, and lease_lost the one fact it cannot carry (an ended lease answers renew 404 UNKNOWN_LEASE).
• docs/CONFIGURATION.md — lease.defaultTtlMs is request-only and explicitly not the renew fallback; lease.maxTtlMs added, with a note that it bounds what is asked for and is not re-applied to leases that already exist; retired keys are a migration table with no aliasing; validation distinguishes reject-at-load from warn-and-ignore.
• docs/ARCHITECTURE.md — "Leases" rewritten around one kind of lease (stored ttlMs, lastRenewedAt, renew-failure semantics, the SIGKILL cost). Topology bullets lose "connection close = release" and "the connection is the lease heartbeat"; MCP's two reconnect triggers spelled out; the contract section states the {min: 4, max: 4} range; startup restores every lease's timer with no orphan sweep; the admin example includes lease renew; notices corrected to HTTP-side; bare "ADR §10/§11" references spelled out as ADR 0003.
• docs/EVENTS.md — the note cites the ADR's Consequences bullet; the four lease rows are marked implemented (payload per ADR 0004 pending).
• docs/known-pitfalls.md — new "A SIGKILLed lease holder keeps its device until the TTL expires". The reparented-holder pitfall reframed (a TTL bounds silence, and a live renewing holder is not silent). The HTTP-tracker pitfall explains itself by a polling client being absent between calls, not by a connection holding something.
• docs/ABOUT.md, README.md — one TTL lease kind everywhere; both grant examples carry ttlMs/lastRenewedAt and drop mode; MCP's paragraph says manual lease renewal and that the server renews its own session's lease; the MCP cross-link points at CLI.md's real heading anchor.

Breaking changes the changelog lists

## Unreleased, in 0.3.0's style, opening with a note that ADR 0004 is accepted-but-unimplemented and these entries land with PRs A and B. Breaking: lease.heartbeat and the heartbeat capability removed; mode out of lease.request and the lease record; a body-less renew re-applying the lease's own TTL; lastRenewedAt as a new stored field; protocol 4; three config keys retired with no alias plus the fail-closed validation rule; the upgrade case for a lease a pre-ADR-0004 daemon persisted in held mode (deadline survives, nothing can renew it on protocol 4, it expires or is released); the SIGKILL bound; daemon stop not releasing and no startup sweep; the two dropped lease.released reasons; onLeaseLost not firing on connection loss; simlock lease exiting 1 on a dead connection; and the MCP renew timer's reconnect that never launches a daemon.

Review history

Round 1 (not isolated — this session has no Agent/Task tool, so I ran the checklist myself): 4 findings → 250e479.
Round 2 (isolated): MERGE AFTER FIXES, 15 findings → 146c910.
Round 3 (isolated): MERGE AFTER FIXES, 14 findings → 0ce1dba.
Round 4 (isolated): MERGE AFTER FIXES, 4 blocking + 3 should-fix + nits → dba8292. Every blocking finding was "the ADR does not record what the docs settle", fixed by moving the decision into the ADR.
Round 5 (confirmation): all twelve settled points CONSISTENT across ADR and docs; one gap and three nits → 7b3d244.
From PR B's code review → 679ebcc: a config-rejected daemon boot does not surface as DAEMON_STARTUP_FAILED — that validation runs before the socket is claimed, so an auto-starting command's launch times out and it fails with exit 1 (INTERNAL), the reason being in simlock daemon logs. (DAEMON_STARTUP_FAILED in ARCHITECTURE.md is the other case — convergence throwing after the socket claim — and is correct as-is.) The DAEMON_CONNECTION_LOST sample also used an em dash where the code writes ASCII --.
From PR B's second code review → c8ff5b4, two cases about a lease that already exists when something changes around it:

Addition	What it says
lease.maxTtlMs is not retroactive (docs/CONFIGURATION.md)	The cap bounds what a request or renew may ask for, and is not re-applied to existing leases. A lease holding a larger stored ttlMs — granted under a higher cap, or carried over from an older record — keeps re-applying that width on every body-less renew, so lowering the cap does not shorten it; release it, or renew once with an explicit smaller --ttl.
Upgrading over a live held lease (CHANGELOG.md)	A lease a pre-ADR-0004 daemon persisted in held mode survives the upgrade with its deadline intact, up to the old one-hour lease.heldTtlBackstopMs. Nothing can renew it — its holder speaks protocol 3, the new daemon advertises {min: 4, max: 4}, so its hello fails. It expires on that deadline, or simlock release <lease-id> ends it sooner; stopping the old daemon while idle, as the protocol-mismatch error already advises, avoids it entirely.

Validation (re-run after each round)

• pnpm run format:check and pnpm run lint — clean.
• All three grant samples parsed as JSON and asserted consistent: ttlDeadline == grantedAt + ttlMs, lastRenewedAt == grantedAt, no mode key. The DAEMON_CONNECTION_LOST sample is parsed too, and asserted free of non-ASCII dashes.
• Word-level diff of every changed file against the previous commit on each round: each change region is exactly one intended edit, which is how the whole-list re-flows in 0ce1dba were bounded.
• Every relative markdown link and heading anchor across all 25 tracked .md files resolves.
• Retired-identifier grep — every hit deliberate: ADR 0003/0004 quoting the history they narrow, CONFIGURATION's migration table, the changelog naming removed keys and the old backstop in the upgrade note, and the places explaining why lastRenewedAt is not a rename.
• No remaining TTL phrasing; no doc calls lease.defaultTtlMs the renew fallback; no added prose line exceeds the wrap width.
• git diff --name-only against the base touches nothing under src/, e2e/, or docs/agent-rules/ — 12 files, all .md.

Pre-existing hook bug, tracked as #126: .oxfmtrc.json sets ignorePatterns: ["docs/**"], but lefthook's pre-commit format job runs oxfmt --check {staged_files}. A commit staging only files under docs/ hands oxfmt zero targets and it exits 2 ("Expected at least one target file"), failing the hook on a perfectly-formatted change. 679ebcc is docs-only and hit this; it was committed with --no-verify after confirming repo-wide format:check and lint both pass. skip_empty: true on that job, or narrowing its glob to exclude docs/, would fix it.

🤖 Generated with Claude Code

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